Extreme pressure lubricants



United States Patent,

3,139,405 EXTREME PRESSURE LUBRICANTS Homer H. Farmer, Westport, and Harold F. Tompkins,

Fairfield, Conn., assignors to R. T. Vanderbilt Company, Inc., New York, N.Y., a corporation of New York No Drawing. Filed May 29, 1961, Ser. No. 113,150 6 Claims. (Cl. 252-33.6)

The present invention pertains to lubricants, and more particularly to extreme pressure lubricants.

With some types of gears, such as hypoid gears, and with heavily loaded bearings where both high pressure and high rubbing velocity occur, it is extremely diflicult to maintain a thin film of lubricant between the bearing surfaces. When the film of lubricant ruptures, the mating high spots where metal-to-metal contact occurs are deformed and plow into each other resulting in localized welding. As the weld is sheared by the relative motion of the surfaces, particles of metal are removed. The contacting surfaces become rough and pitted and eventually fail by seizing or scoring.

The special types of lubricants developed for use under these conditions are known as extreme pressure or E.P. lubricants. The E.P. lubricants are made by adding special E.P. agents to lubricating oils or to greases.

, Often other agents are also added, such as oiliness agents and anticorrosion agents.

Extreme pressure lubricants may prevent localized welding by reacting with the bearing surfaces. Some E.P. agents are thought to react with the surfaces to form low melting alloys, while others are thought to react to form easily sheared inorganic films.

It has been proposed heretofore to add some metallic salts of dialkyldithiocarbamic acids, e.g., tin diamyldithiocarbamate, lead diamyldithiocarbamate, and selenous diamyldithiocarbamate, as E.P. agents to mineral lubricating oils in order to form extreme pressure lubricants. While the extreme pressure properties of the lubricants are slightly improved by the use therein of these E.P. agents, nevertheless the lubricants so produced do not have the high load-carrying capacity or passing load now demanded by some present-day equipment subjected to unusually high pressures.

In accordance with the present invention there is provided an extreme pressure lubricating composition which has a load-carrying capacity or passing load which is exceedingly high and heretofore unobtainable by practical means. The extreme pressure lubricating composition of the invention comprises an oil or grease of mineral or synthetic origin, i.e., a lubricant, and a novel E.P. agent.

The lubricating oil base stock used in preparing the lubricant may be straight mineral lubricating oils or distillates, bright stock residua and the like. Synthetic lubricating oils, such as hydrogenated oils, glycol ethers, dibasic acid esters, and other polyester and polyether synthetic lubricating oils can be used. Mixtures of synthetic lubricating oils and petroleum base mineral oils can also be employed. The lubricating oil base stock will generally have a viscosity in the range of from about 40 to 150 seconds Saybolt viscosity at 210 F.

The novel E.P. agent or additive in the extreme pressure lubricating composition of the invention is antimo nous diamyldithiocarbamate or antimonous dihexyldithiocarbamate. These materials can be readily prepared by reacting together antimony trioxide, carbon disulfide and commercial diamyl amine or dihexyl amine in accordance with the general process disclosed in US. Patent No. 2,492,314. The antimonous diamyldithiocarbamate or antimonous dihexyldithiocarbamate is present in the extreme pressure lubricating composition in an amount from 3,139,405 Patented June 30, 1964 "ice about 2.5% to'about 5%, and preferably about 2.5%,

, based on the weight of the lubricating oil or grease, i.e.,

terized by having an exceptionally high Timken loadcarrying capacity or passing load. Indeed, a Timken loadcarrying capacity as high as 100 pounds can be obtained with a lubricant using the preferred amount of the antimonous diamyldithiocarbamate E.P. agent.

If desired, the extreme pressure lubricating composi tion can contain various optional components, such as oiliness agents, anticorrosion agents, pour depressants and other E.P. agents; The extreme pressure lubricating composition of the invention can be used for .a-number of heavy duty purposes, such as a gear oil, cutting oil and metal working lubricant.

The amazingly high load-bearing capacity imparted to lubricants by the addition thereto of antimonous diamyldithiocarbamate or antimonous dihexyldithiocarbamate is carbamic acids impart only moderate or low load-bearing capacities to lubricants. This isreadily demonstrated by the comparative data set forth below in Table I.

The data in Table I were obtained in accordance with the following test procedure. To separate portions of a SAE 90 mineral lubricating oil having a viscosity of 87 seconds Saybolt viscosity at 210 F., 1030 seconds Saybolt viscosity at 100 F., and a viscosity index of 91 there were added various metallic salts of dialkyldithiocarbamic acids listed in Table I below to provide a dithiocarbamate content of 1%, 2%, 235%, 3%, 4%, 5%, and 10% based on the weight of the mineral lubricating oil. The lubricating compositions so produced were subjected to the Timken load-bearing test in the Timken Lubricant Tester in which a hardened steel ring rotating at 800 r.p.m. was flooded by the test lubricating composition at 100 F. while a hardened steel block was pressed against it by a system of weights and levers. The highest weight which did not produce scoring of the block in ten minutes running time was recorded as the passing load or O.K. load, which is a recognized measure of the load-carrying capacity of a lubricant. The values obtained in accordance with this standard test are set forth in Table I below.

Table 1 Percent by Weight of Additive in SAE 90 Mineral Lubricating Oil 1 2 2 5 3 4 5 l0 Additive Passing Load Antimonous diamyldithiocarbamate 20 40 100 90 90 70 Antimonous dihexyldithiocarbamate- 50 90 Antimonous dibutyldithiocarbamate 2O 50 80 80 In.o111ble 2 Antimonous di -2-ethylhexy1dithiocarbamate 25 Antimonous didecyldithiocarbamat 25 Lead diamyldithiocarbamate 55 65 60 30 30 30 20 Arsenous diamyldithiocarbamate 20 3O 30 snl ible 1 Selenous diamyldithiocarbamate 1 30 50 50 4O 30 30 Bismuthous diamyldithioearbamate. 30 55 5O 40 40 30 30 Zinc diamyldithiooarbamate 20 30 40 40 40 40 30 Oadimum diamyldithiocarbamate- 30 30 50 50 40 40 Stannic diamyldithiocarbamate 20 3 60 40 Insoluble 2 Bismuthous dibutyldithiocarbamate. Insoluble l Nickelous dibutyldithiocarbamate- Insoluble 2 tion containing from about 2.5% to about 5%, of anti 1%, 2%, 3% and 4% by Weight of the sented in Table II below.

ease roe monous diamyldithiocarbamate or antimonous dihexyldithiocarbamate based on the weight of the mineral lubricating oil have an exceptionally high Timken load-carrying capacity, even as high as 100 pounds, which values were heretofore considered to be unobtainable by practi cal means. None of the comparative lubricants containing analogous or homologous dithiocarbamates could approach the remarkable load-carrying capacity of the extreme pressure lubricating compositions of the invention. Indeed, several of the comparative dithiocarbamate salts were insoluble in the mineral lubricating oil and accordingly did not impart any extreme pressure properties thereto.

, Although the comparative test results given above were obtained with a Timken Lubricant Tester, corroborating data were obtained using the Shell 4-Ball and Falex testing machines.

The Timken load-bearing capacity of a typical grease, namely a lithium 12 -hydroxystearate grease, to which antimonous diamyldithiocarbamate had been added at grease is pre- T able II Percent by Weight of Additive in a lithium 12-hydroxy stearate grease 1 3 3 4 Additive Passing Load Antimonous diamyldithiocarbamate 10 35 80 It Will be appreciated that various modifications and changes in addition to those set forth above may be made in the compositions of the invention without departing from the spirit thereof, and accordingly the invention is to be limited only within the scope of the appended claims.

What is claimed is: 1. An extreme pressure lubricating composition for inhibiting wear, scufling and seizure of engaging movable parts subject to extreme pressures consisting essentially of a lubricant selected from the group consisting of fluid lubricants and greases, and from about 2.5% to about 5% based on the weight of the lubricant of an antimonous dialkyldithiocarbamate extreme pressure additive selected from the group consisting of antimonous diamyldithiocarbamate and antimonous dihexyl-dithiocarbamate.

2. An extreme pressure lubricating composition for inhibiting Wear, scuffing and seizure of engaging movable parts subjectto extreme pressures consisting essentially of a lubricating grease-and from about 2.5% to about 5% based on the weight of the lubricating grease of an anti- I monous dialkyldithiocarbamate extreme pressure additive parts subject to extreme pressures consisting essentially of a mineral lubricating oil and from about 2.5 to about 5% based on the weight of the mineral lubricating oil of antimonous diamyldithiocarbamate as an extreme pressure additive.

5. An extreme pressure lubricating composition for inhibiting wear, scufiing and seizure of engaging movable parts subject to extreme pressures consisting essentially of a mineral lubricating oil and from about 2.5 to about 5% based on the weight of the mineral lubricating oil of antimonous dihexyldithiocarbamate as an extreme pressure additive.

6. An extreme pressure lubricating composition for inhibiting Wear, scufiing and seizure of engaging movable parts subject to extreme pressures consisting essentially of a mineral lubricating oil and about 2.5% based on the.

weight of the mineral lubricating oil of antimonous diamyldithiocarbamate as an extreme pressure additive.

References Cited in the file of this patent UNITED STATES PATENTS 1 2,716,089 Cypers et a1 Aug. 23, 1955 1 I FOREIGN PATENTS 211,212 Australia May 17, 1956 506,167

Canada Sept. 28, 1954 UNITED STATES PATENT OEFQICE C'ETIFICATE OF CORRECTION June 3O 1964 Patent Now 3 l39 LO5 Homer HO Farmer et ale ears in the above numbered pat- It is hereby certified that error app d Letters Patent should read as ent requiring correction and that the sai corrected belouu line 15 thereof for Cciumn 2 Table I first column Cadimum read Cadmium column 3 Table 11 line 2 thereof for ""1 3 3 4" read l 2 3 4 column 4 ",line

42 for Cypers ct alo" rea Signed and sealed this 10th day of November 1964;

(SEAL) Attest:

' EDWARD J. BRENNER ERNEST W. SWIDER Commissioner of Patents Attesting Officer 

1. AN EXTREME PRESSURE LUBRICATING COMPOSITION FOR INHIBITING WEAR, SCUFFING AND SEIZURE OF ENGAGING MOVABLE PARTS SUBJECT TO EXTREME PRESSURES CONSISTING ESSENTIALLY OF A LUBRICANT SELECTED FROM THE GROUP CONSISTING OF FLUID LUBRICANTS AND GREASES, AND FROM ABOUT 2.5% TO ABOUT 5% BASED ON THE WEIGHT OF THE LUBRICANT OF AN ANTIMONOUS DIALKYLDITHIOCARBAMATE EXTREME PRESSURE ADDITIVE SELECTED FROM THE GROUP CONSISTING OF ANTIMONOUS DIAMYLDTHIOCARBAMATE AND ANTIMONOUS DIHEXYLDITHIOCARBAMATE. 